subr_log.c revision 1.10 
1/*	$OpenBSD: subr_log.c,v 1.10 2003/07/21 22:44:50 tedu Exp $	*/
2/*	$NetBSD: subr_log.c,v 1.11 1996/03/30 22:24:44 christos Exp $	*/
3
4/*
5 * Copyright (c) 1982, 1986, 1993
6 *	The Regents of the University of California.  All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 *	@(#)subr_log.c	8.1 (Berkeley) 6/10/93
33 */
34
35/*
36 * Error log buffer for kernel printf's.
37 */
38
39#include <sys/param.h>
40#include <sys/systm.h>
41#include <sys/proc.h>
42#include <sys/vnode.h>
43#include <sys/ioctl.h>
44#include <sys/msgbuf.h>
45#include <sys/file.h>
46#include <sys/signalvar.h>
47#include <sys/syslog.h>
48#include <sys/conf.h>
49
50#define LOG_RDPRI	(PZERO + 1)
51
52#define LOG_ASYNC	0x04
53#define LOG_RDWAIT	0x08
54
55struct logsoftc {
56	int	sc_state;		/* see above for possibilities */
57	struct	selinfo sc_selp;	/* process waiting on select call */
58	int	sc_pgid;		/* process/group for async I/O */
59	uid_t	sc_siguid;		/* uid for process that set sc_pgid */
60	uid_t	sc_sigeuid;		/* euid for process that set sc_pgid */
61} logsoftc;
62
63int	log_open;			/* also used in log() */
64int	msgbufmapped;			/* is the message buffer mapped */
65int	msgbufenabled;			/* is logging to the buffer enabled */
66struct	msgbuf *msgbufp;		/* the mapped buffer, itself. */
67
68void filt_logrdetach(struct knote *kn);
69int filt_logread(struct knote *kn, long hint);
70
71struct filterops logread_filtops =
72	{ 1, NULL, filt_logrdetach, filt_logread};
73
74void
75initmsgbuf(buf, bufsize)
76	caddr_t buf;
77	size_t bufsize;
78{
79	register struct msgbuf *mbp;
80	long new_bufs;
81
82	/* Sanity-check the given size. */
83	if (bufsize < sizeof(struct msgbuf))
84		return;
85
86	mbp = msgbufp = (struct msgbuf *)buf;
87
88	new_bufs = bufsize - offsetof(struct msgbuf, msg_bufc);
89	if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
90	    (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
91	    (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
92		/*
93		 * If the buffer magic number is wrong, has changed
94		 * size (which shouldn't happen often), or is
95		 * internally inconsistent, initialize it.
96		 */
97
98		bzero(buf, bufsize);
99		mbp->msg_magic = MSG_MAGIC;
100		mbp->msg_bufs = new_bufs;
101	}
102
103	/* mark it as ready for use. */
104	msgbufmapped = msgbufenabled = 1;
105}
106
107/*ARGSUSED*/
108int
109logopen(dev, flags, mode, p)
110	dev_t dev;
111	int flags, mode;
112	struct proc *p;
113{
114	if (log_open)
115		return (EBUSY);
116	log_open = 1;
117	return (0);
118}
119
120/*ARGSUSED*/
121int
122logclose(dev, flag, mode, p)
123	dev_t dev;
124	int flag, mode;
125	struct proc *p;
126{
127
128	log_open = 0;
129	logsoftc.sc_state = 0;
130	return (0);
131}
132
133/*ARGSUSED*/
134int
135logread(dev, uio, flag)
136	dev_t dev;
137	struct uio *uio;
138	int flag;
139{
140	register struct msgbuf *mbp = msgbufp;
141	register long l;
142	register int s;
143	int error = 0;
144
145	s = splhigh();
146	while (mbp->msg_bufr == mbp->msg_bufx) {
147		if (flag & IO_NDELAY) {
148			splx(s);
149			return (EWOULDBLOCK);
150		}
151		logsoftc.sc_state |= LOG_RDWAIT;
152		error = tsleep(mbp, LOG_RDPRI | PCATCH,
153			       "klog", 0);
154		if (error) {
155			splx(s);
156			return (error);
157		}
158	}
159	splx(s);
160	logsoftc.sc_state &= ~LOG_RDWAIT;
161
162	while (uio->uio_resid > 0) {
163		l = mbp->msg_bufx - mbp->msg_bufr;
164		if (l < 0)
165			l = mbp->msg_bufs - mbp->msg_bufr;
166		l = min(l, uio->uio_resid);
167		if (l == 0)
168			break;
169		error = uiomove(&mbp->msg_bufc[mbp->msg_bufr], (int)l, uio);
170		if (error)
171			break;
172		mbp->msg_bufr += l;
173		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
174			mbp->msg_bufr = 0;
175	}
176	return (error);
177}
178
179/*ARGSUSED*/
180int
181logselect(dev, rw, p)
182	dev_t dev;
183	int rw;
184	struct proc *p;
185{
186	int s = splhigh();
187
188	switch (rw) {
189
190	case FREAD:
191		if (msgbufp->msg_bufr != msgbufp->msg_bufx) {
192			splx(s);
193			return (1);
194		}
195		selrecord(p, &logsoftc.sc_selp);
196		break;
197	}
198	splx(s);
199	return (0);
200}
201
202int
203logkqfilter(dev_t dev, struct knote *kn)
204{
205	struct klist *klist;
206	int s;
207
208	switch (kn->kn_filter) {
209	case EVFILT_READ:
210		klist = &logsoftc.sc_selp.si_note;
211		kn->kn_fop = &logread_filtops;
212		break;
213	default:
214		return (1);
215	}
216
217	kn->kn_hook = (void *)msgbufp;
218
219	s = splhigh();
220	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
221	splx(s);
222
223	return (0);
224}
225
226void
227filt_logrdetach(struct knote *kn)
228{
229	int s = splhigh();
230
231	SLIST_REMOVE(&logsoftc.sc_selp.si_note, kn, knote, kn_selnext);
232	splx(s);
233}
234
235int
236filt_logread(struct knote *kn, long hint)
237{
238	struct  msgbuf *p = (struct  msgbuf *)kn->kn_hook;
239
240	kn->kn_data = (int)(p->msg_bufx - p->msg_bufr);
241
242	return (p->msg_bufx != p->msg_bufr);
243}
244
245void
246logwakeup()
247{
248	if (!log_open)
249		return;
250	selwakeup(&logsoftc.sc_selp);
251	if (logsoftc.sc_state & LOG_ASYNC)
252		csignal(logsoftc.sc_pgid, SIGIO,
253		    logsoftc.sc_siguid, logsoftc.sc_sigeuid);
254	if (logsoftc.sc_state & LOG_RDWAIT) {
255		wakeup(msgbufp);
256		logsoftc.sc_state &= ~LOG_RDWAIT;
257	}
258	KNOTE(&logsoftc.sc_selp.si_note, 0);
259}
260
261/*ARGSUSED*/
262int
263logioctl(dev, com, data, flag, p)
264	dev_t dev;
265	u_long com;
266	caddr_t data;
267	int flag;
268	struct proc *p;
269{
270	long l;
271	int s;
272
273	switch (com) {
274
275	/* return number of characters immediately available */
276	case FIONREAD:
277		s = splhigh();
278		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
279		splx(s);
280		if (l < 0)
281			l += msgbufp->msg_bufs;
282		*(int *)data = l;
283		break;
284
285	case FIONBIO:
286		break;
287
288	case FIOASYNC:
289		if (*(int *)data)
290			logsoftc.sc_state |= LOG_ASYNC;
291		else
292			logsoftc.sc_state &= ~LOG_ASYNC;
293		break;
294
295	case TIOCSPGRP:
296		logsoftc.sc_pgid = *(int *)data;
297		logsoftc.sc_siguid = p->p_cred->p_ruid;
298		logsoftc.sc_sigeuid = p->p_ucred->cr_uid;
299		break;
300
301	case TIOCGPGRP:
302		*(int *)data = logsoftc.sc_pgid;
303		break;
304
305	default:
306		return (-1);
307	}
308	return (0);
309}
310